Efficacy of Carica papaya, Citrus sinensis and Picralima nitida against cowpea Bruchid callosobruchus maculates and maize weevil, Sitophilus zeamais in storage

Abstract

Efficacy of the leaf powders of Carica papaya, Citrus sinensis, Picralima nitida and permethrin dust against Callosobruchus maculatus and Sitophilus zeamais in stored bean and maize was conducted. Treatments were admixed with 50 g of bean and maize and infested with 20 adults of C. maculatus and S. zeamais in 200 ml air-tight vials containing 0.0, 2.5, 5.0, 7.5 and 10.0 g of the plant powders and permethrin dust and were kept under prevailing laboratory conditions (60 – 65 RH, 27 ± 2⁰C) for a period of 96 hours. The experiment was laid out in completely randomized design of 5 treatments and four replicates. The mortality of weevils to the plant powders and the synthetic insecticides were recorded. The highest mortality occurred in the permethrin dust followed by C. papaya, C. sinensis and P. nitida. Mortality rate for C. maculates and S. zeamais were 14.10 ± 12.43 and 12.95 ± 8.41 in permethrin dust, 10.95 ± 7.99 and 4.00 ± 4.52 in C. papaya powder, 8.25 ± 5.89 and 3.05 ± 3.30 in C. sinensis powder and 8.10 ± 6.60 and 2.40 ± 2.70 in P. nitida powder. The highest mortality count in all the treatments occurred in the 48 to 96 hours, while the least mortality was observed within the 24 hours. The mortality was higher in the treatments with the higher dose of the powders. The insecticidal effects were more in C. maculatus than in S. zeamais. No mortality was recorded in the control experiment.

Keywords: Efficacy, Botanicals, Carica papaya, Citrus sinensis, Picralima nitida, Callosobruchus maculates, Sitophilus zeamais